Double Expansion Boiler Tube Plug

ABSTRACT

The following substitute specification does not contain and new matter as that submitted in the Provisional Patent Application No. 61/018,908 filed on Jan. 4, 2008. The boiler plug system of the invention is intended for plugging leaks in the steel tube flue gas-to-water heat exchangers of steam boilers. The boiler plug of the invention is adaptable to the varied sizes of heat exchanger tubes. In this specification, the elements of the invention will be described as applied to two (2) inch ID (inside diameter) steel tubing heat exchangers with the understanding that the boiler plug of the invention can be made smaller or larger as the particular application may require. The boiler plug of the invention is readily adaptable to heat exchanger tubing of one and one-half (1.5) to three (3) inch ID. 
     The boiler heat exchanger panel consists of a closely packed bundle of lengthy steel tubes having a diameter of about two (2) inches. Hot flue gasses passing from the firebox exchange heat through the tube wall with circulating water. Due to the hot flue gasses corrosive nature, tubing leaks frequently occur. These leaks must be corrected relatively promptly before a leak compromises the integrity of adjoining tubes and worsens the problem. 
     The boiler plug of the instant invention seals the tube at the point of the leak by combining two techniques:
         1. Inserting a copper sleeve of a slightly smaller diameter than the faulty tube into the faulty tube, and two (2) tapered, cast-iron plugs of a slightly smaller diameter than the sleeve until the sleeve is directly over the corroded area of the tube;   2. Threading a bolt through the center of both plugs and then tightening the plugs together. By this technique, the rod brings the cast-iron plugs together within the copper sleeve and compresses the copper sleeve against the inner surface of the tube thus sealing the leak. This eliminates the need to drain and cool the boiler before the tube can be patched from both ends or replaced.       

     The major parts of the boiler plug of the instant invention are as follows: A tool smaller than the diameter of the tube the length of which can be adjusted depending on the length of the tube. A sleeve made of an outer layer of rubber and an inner layer of copper having a maximum circumference marginally smaller than the circumference of the tube. Two (2) tapered plugs made of cast-iron with a slightly smaller diameter than the sleeve which are threaded onto a threaded steel bolt which has a cap on one end the same diameter of the sleeve. The rod is longer than the length of the plug-sleeve assembly allowing the tool to be threaded onto it. 
     An important element of the boiler plug of the instant invention is the design and composition of the sleeve. When the plugs are pulled together inside the sleeve, by turning the tool onto the threaded bolt, the plugs are forced together compressing the sleeve against the interior of the tube, thereby sealing the tube end and assuring the end of the leakage. 
     Another important element of the invention is the design of the tool. The tool, which is reusable, can be made longer or shorter by the use of extension pieces and may be used with any length or diameter tubing. 
     It is to be understood that the present invention is not limited to the embodiments described above, but encompasses any and all embodiments within the scope of the following claims.

This application is based on Provisional Patent Application No. 61/018,908 filed on Jan. 4, 2008 The priority of which is hereby claimed. The specification contained herein does not contain any new matter as stated in Provisional Patent Application No. 61/018,908.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to fire tube steam boilers. The invention particularly relates to an apparatus for quickly and inexpensively plugging water leaks in the tubing of fire tube steam boilers without having to drain and cool the boiler.

2. Description of the Related Art

Fire tube steam boilers are in demand today for applications in industrial, commercial and public buildings. The fire tube steam boiler system is a vintage technology that has a long life when properly maintained. However, over time or under unusual circumstances leaks develop in the flue gas-to-water steel tube heat exchanger or conduits. These leaks, if unattended, will quickly damage other parts of the tubular heat exchanger bundle and can require a major overhaul or replacement of the entire heat exchanger. In that eventuality, the boiler may be out of service for an unacceptable length of time while the exchanger is being replaced and be a much more costly repair alternative.

Repair to the boiler tube leak requires a prompt plugging of the faulty tube with a tubing cross-sectional plug at both ends of the tube. The problem lies in the fact that access to the tubes is only open on one end of the boiler. Thus, in order to repair the tube with conventional means, the technician must enter the boiler. Because the boiler is far too hot to enter, the technician must follow the following process:

-   -   1. Shut down boiler     -   2. Open boiler chamber     -   3. Drain boiler     -   4. Wait for boiler to cool     -   5. Replace the faulty tube

This process can take hours if not days. This has been the answer to tube leaks for many years.

U.S. Pat. No. 5,016,674 to Kiss claims a plug for leaky tubes of a heat exchanger. The plug consists essentially of a frustrum shaped tapered hollow plug with the diameter of the top of the frustrum being the widest of the plug. A plug nut is formed on the top of the plug as part of the plug as manufactured. A threaded rod is connected to the plug nut by passing through the hollow plug; the exposed end of the rod receives a gasket and a rod nut. An “O” ring is inserted inside the leaky tube around the plug. The plug diameter at the top is less than the outside diameter of the end of the tube. Accordingly, nothing protrudes past the outside surface of the end of the tube. This allows close packing of the tubes of the heat exchanger bundle. It is claimed that the “O” ring itself, once compressed by tightening the rod nut, forms a seal that prevents the water and hot gas from mixing. This remedy still requires the technician to access both sides of the tube using the above process.

U.S. Pat. No. 685,561 to Bettermann describes a flue plug for plugging the ends of a boiler flue. The plugs are tapered in shape with annular flanges dished on their under sides. A connecting rod passes through the two plugs with a means for tightening the plugs to push the ends of the plugs into the ends of the flue. This remedy still requires the technician to access both sides of the tube using the above process.

U.S. Pat. No. 20,060,277,756 to Ivery describes a method of plugging the ends of tubes in low pressure steam boilers. The invention uses a cap containing a gasket channel of the same diameter as the edge of the tube. The underside cylindrical wall of the cap contains an aperture in common with that of the top of the cap. A threaded rod is passed through the cap and connected to an identical plug on the other end of the tube. Simultaneously tightening hex nuts on the two rods seals the tubing ends. This remedy still requires the technician to access both sides of the tube using the above process.

None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed. Thus, a boiler plug solving the aforementioned problems of leak sealing from opening one end of the boiler only is desired.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view cutaway of the boiler tube plug.

FIG. 2 is a side view of the rear plug.

FIG. 3 is a side view of the front plug.

FIG. 4 is a side view of the sleeve for the boiler tube plug.

FIG. 5 is a side view of the threaded bolt.

FIG. 6 is side views of the boiler tube plug installation tool.

FIG. 7 is a view of a boiler showing the position of the boiler tubes.

FIG. 8 is a side view of the boiler tube plug assembly as it is to be inserted into the boiler tube.

Similar reference characters denote corresponding features consistently throughout the attached drawings.

SPECIFICATION

A Rear Plug B Front Plug C Tick Sleeve D Screw Compressor E Installation Tools E1 Extension Coupler F Boiler Tube

Boiler Tube Measurements 2″ 2-1/2″ 3″ Rear Plug Outside Width 1-5/8″ 2-1/8″ 2-5/8″ Rear Plug Inside Width 1-1/8″ 1-5/8″ 2-1/8″ Rear Plug Height 3-1/4″ 3-1/4″ 3-1/4″ Rear Plug Hole with Tapping 1/2″ 1/2″ 1/2″ Front Plug Outside Width 1-5/8″ 2-1/8″ 2-5/8″ Front Plug Inside Width 1-1/8″ 1-5/8″ 2-1/8″ Front Plug Height 3-1/4″ 3-1/4″ 3-1/4″ Front Plug Hole 5/8″ 5/8″ 5/8″ Tick Sleeve Diameter 1-1/2″ 2″ 2-1/2″ Tick Sleeve Length 8″ 8″ 8″ Tick Sleeve Rubber Insulation 1/16″ 1/16″ 1/16″ Tick Sleeve 1/8″ 1/8″ 1/8″ 

1. In a boiler plug repair system, the combination of an adjustable length tool; a tubular sleeve; two tapered plugs; a threaded bolt longer in length than the plug-sleeve assembly, which has a cap on its end the same diameter as the sleeve.
 2. The combination in claim 1, wherein the tool can be adjusted depending of the length of the boiler tube and is of a smaller diameter than the diameter of the boiler tube and has a mechanism by which.
 3. The combination of claim 1, wherein sleeve used to seal the leak is comprised of an outer layer of rubber and an inner layer of copper.
 4. The combination of claim 1, wherein said threaded bolt full threaded rod.
 5. The combination of claim 1, wherein said tapered plug is made of cast-iron.
 6. A method for sealing leaking boiler heat exchanger tubes comprising the combination in claim 1; inserting the combination of the sleeve, plugs, threaded bolt into the tube, turning the tool which is connected to the threaded bolt which forces the plugs into the sleeve, expanding the sleeve and sealing the leak. 